Coconut water is the liquid endosperm of Cocos nucifera L an is used as a supplement in media for the growth of plant tissue cultures. The coconut fruit is unique in that it accumulates large amounts of this liquid over periods of a year or more in its life cycle. The greatest amount of coconut water is found in young, green coconuts and provides nourishment for the growth of the solid endosperm (coconut meat) inside the hard shell of the fruit. When the fruit matures, both the solid endosperm and the remaining coconut water serve as nutrients for the developing embryo and seedling. Thus coconut water serves as a natural reservoir of nutrients to promote tissue growth1.
The nutritional composition of coconut water obtained from fruits at different stages of maturity has been determined. The medium is rich in proteins, amino acid sugars, vitamins, minerals and growth hormones (Table 1) essential to the promotion of tissue growth. In addition, shikimic acids and quinic acids have been detected in samples of coconut water from fruits at different stages of maturity, with the maximum amounts being found in young green coconuts. The probable role of these alicyclic acids in romatic biosynthesis, indicates their importance in the developing coconut. They may also play a significant role in the nutrition of plant and tissue cultures.
TABLE 1VITAMIN, GROWTH FACTOR, SUGAR ALCOHOL ANDMINERAL CONTENT OF COCONUT WATER   COMPOUNDMg/LNicotinic acid0.64Pantothenic acid0.52Biotin0.02Riboflavin0.01Folic acid0.003ThiamineTracePyridoximeTraceAuxin0.07Gibberellin*1,3-Diphenylurea5.8Sorbitol15.0M-inositol0.01Scyllo-inositol0.05Mg/100 gPotassium312.0Chloride183.0Sodium105.0Phosphorous37.0Magnesium30.0Sulfur24.0Iron0.10Copper0.04* A significant growth response was obtained from dwarf peas with an extract of 188 ml of coconut water.
The RNA-phosphorus (RNA-P) content of coconut water was found to be consistently high at all levels of fruit maturity (Table 2). The ratio of RNA-P/DNA-P was unusually high. The role of RNA in amino acid transport and respiratory metabolism of living cells is well known. The RNA of coconut water would therefore effectively carry out these and other functions as part of the metabolic machinery essential to the developing endosperm tissue of the coconut and therefore support the growth of other living cells as well, in tissue culture media.
TABLE 2RNA-PHOSPHORUS AND DNA-PHOSPHORUS OF THEALCOHOL-INSOLUBLE RESIDUE FROM COCONUT WATERμG/mg alcohol-insolubleresidueRatioAge of coconutsRNA-PDNA-PRNA-P/DNA-PYoung green20.050.06342.5Mature, green32.822.4513.9
Cytokinins are a class of plant growth substances (plant hormones) active in promoting cell division. They are also involved in cell growth and differentiation and in other physiological processes. A major cytokinin found in coconut milk was isolated using a standard procedure, the tobacco callus growth-promoting assay. The structure was determined to be a complex trans-zeatin riboside (G3A2-ZR). The authors of this study attributed at least 20% of the cytokinin activity in coconut milk to this compound2.
A study that explored the efficacy of single and combined growth regulator treatments of indole-3-acetic acid (IAA), gibberelic acid (GA3) and coconut milk on plant height, yield, chlorophyll and vitamin contents of plants such as Abelmoschus esculetus L and Solanum gilo L, found that 100 mg/L GA3 and 15% coconut water were significantly effective treatments3.
The nutritive properties of coconut water are well recognized in Oriental tradition. Immature coconuts are used as a glucose-electrolyte oral re-hydration solution for treatment of diarrhea4. Coconut water solids also provide a nutritive medium for beneficial microflora in the gastrointestinal tract. A recent report also mentions the successful use of coconut water as a short-term intravenous hydration fluid5. Coconut water has been used traditionally as a nutritional beverage. The FAO was recently granted a patent in the UK for the manufacture of bottled coconut water that retained all nutrients. This is the first patent given to a UN agency. Unlike existing methods their process did not use HTST pasteurization, wherein heat treatment would inactivate some of the biological activity of the coconut water.
Other researchers have obtained an extract from coconut water and milk called Cocogro, a natural product comprised of plant growth hormones and regulators, which enhances the growth of vegetables, legumes fruit trees, cereal crops, flowering plants, etc.
Green coconut milk is reported to be an effective culture medium for animal cells (Rev Bras Biol. 1970(Apr) 30:1:97-100) and Plasmodium (Trans. R. Soc. Trop. Med Hyg. 1989 83:5, 720). A major cytokinin, G3A2-ZR, was also identified in coconut milk (Kobayashi, H: et al. Experentia, 1995 51:11 1081-84).
Although coconut milk has been used traditionally on the skin as a nourishing agent, green coconut water provides unique nutrients for sustaining cell growth. For example, a protein fraction isolated from coconut water was absent in the milk (Birosel, DM et al. Rev. Farm Bioquim Univ Sao Paulo 1976 14:35-42).
Coconut milk is used in a facemask in U.S. Pat. No. 5,660,840 and in a plant growth regulating composition in U.S. Pat. No. 5654255.
Coconut water was found to be safe for topical use. In laboratory studies, the material is shown to have no irritating effects on the skin, and the LD50 value must be greater than 2000 mg/kg when administered through the skin. Accordingly, coconut water is nontoxic.
Coconut water is described as an isotonic sports drink. The comparative properties of coconut water and conventional sports drinks are listed in Table 37:
TABLE 3SPORTS DRINKS VS. COCONUT WATERSports drinksCoconut waterComponent(mg/100 ml)(mg/100 ml)Potassium11.7294Sodium4125Chloride39118Magnesium710Sugars65